<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>Bootstrap 101 Template</title>

        <!-- Bootstrap -->
        <link href="css/bootstrap.min.css" rel="stylesheet">

        <!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
        <!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
        <!--[if lt IE 9]>
          <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
          <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
        <![endif]-->
        <style>
            div {display: block; border: 1px solid black }
            #container { overflow: hidden;  }
            .item { height: 30px; }
        </style>
    </head>
    <body>
        <div id="container">
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">aaaaaaaaa</div>
        <div class="item">bbbbbbbbb</div>
        <div class="item">ccccccccc</div>
        <div class="item">ccccccccc</div>
        </div>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
        <script src="js/bootstrap.min.js"></script>
    </body>
    <script>
        $(document).ready(function() {
            var total= 0;
            $(".item").each(function(){
                var height = $(".item").height();
                total = height + total;
            });
            $("#container").height(total/2);
        });
    </script>
</html>
